Improved thermoplastic skin packing means

ABSTRACT

A package containing skin-packed perishable goods including a base, goods on the base, a flexible plastic web over the goods and the base to, at least partially, skin pack the goods, and a lid for the base. A gas to permeate the web and enhance preservation of the goods is contained in the space between the lid and the skin packed goods.

FIELD OF THE INVENTION

This invention relates to improved packaging and relates particularly,but not exclusively, to improved packaging for containing meat, fish,poultry, vegetables or other food products.

DESCRIPTION OF THE PRIOR ART

Hitherto, in the art of packaging meat, fish, poultry, vegetables orother food products, it has been a problem to (a) provide for relativelylong shelf life of the packaged goods, (b) to provide a package whichwill not affect the appearance or keeping qualities of the packagedgoods, (c) to provide a package which is relatively simple tomanufacture, (d) to provide an inexpensive yet sufficiently strongpackage and (e) to provide a package wherein fogging of the package frommoisture carried in the packaged goods will be inhibited.

Packaging has been known which includes certain gases to enhance thekeeping qualities of the contents. For example, it is known to usepackaging such as disclosed in PCT Patent Application No.PCT/AU85/00131, the subject matter of which is hereby incorporated byreference. The shelf life of the packaged goods can thereby be enhanced.Typically these packages are made from a plastics material and theplastics material provides a partial barrier to the ingress of unwantedgases. Some of the plastics material is such that it allows gases whichmay generate within the package to escape. Other known plasticsmaterials allow certain gases to permeate enhancing the keepingqualities of the packaged goods.

STATEMENT OF THE INVENTION

The present invention attempts to overcome one or more of theaforementioned problems by including a skin wrapping in the totalpackage. Skin packing is a known technique where goods are tightlypackaged within a wrapping material and where substantially all of theatmospheric air is excluded. This known technique has been utilized toprovide a different packaging method and structure than hitherto known.

According to a first broad aspect of the present invention, there may beprovided a method of packaging goods which, in general terms, includesplacing perishable goods in a base, placing a web of flexible materialover the base and the goods, allowing the flexible web to displaceitself over and, thereby, at least partially skin pack the goods,applying a lid to the base over the flexible web, sealing the lid andthe flexible web to the base, and charging the space between the lid andthe flexible web with a gas that will permeate the flexible web andprolong preservation of the package goods.

According to a further aspect of the present invention there may beprovided an improved package in which perishable goods placed on a baseare at least partially skin packed by a flexible plastic web. The baseis covered by a lid, which creates a space between the skin packed goodsand the lid. The lid and the flexible web are sealed to the base and agas selected for preserving the skin wrapped goods is introduced intothe space. The flexible skin packing web is permeable to the gas.

Most preferably said desired gas has sufficient volume and is of such atype that it will enhance the keeping qualities of the packaged goods.

It is also preferred that there be a further web of plastics materialbetween said base and said goods so that said goods will besubstantially enclosed in a skin packing by said flexible web and saidfurther web and substantially without any air therebetween.

Another aspect of the invention is an apparatus for making the improvedpackage. This apparatus includes a station where the goods placed on thebase are at least partially skin packed. The apparatus further includesa lid sealing station which the package under assembly sequentiallyreaches after the skin packing station. Here, the lid is sealed to thebase, and a desired gas inserted into the space between the skin-packingweb and the lid.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS

In order that the invention can be more clearly ascertained theconstruction of preferred embodiments will now be described withreference to the accompanying drawings wherein:

FIGS. 1 through 5 diagrammatically represent side views of fivedifferent types of packaging within the scope of the present invention;

FIG. 6 is a schematic side view of one preferred machine used forperforming a preferred method of the present invention;

FIG. 7 is a close-up side cross-sectional view of a station of themachine where a web of plastics material is skin packaged over goods onthe base;

FIG. 8 is a view similar to that of FIG. 7 but showing a gas flushingstation;

FIG. 9 is a diagrammatical side view of a different type of packagingwithin the scope of the present invention;

FIG. 10 is a diagrammatic side view of a preferred machine for makingthe package shown in FIG. 9; and

FIG. 11 is a plan view of a preferred insert for use in the packageproduced by the machine of FIG. 9.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to FIG. 1 there is shown packaging made of plasticsmaterials. The packaging comprises a generally rectangular shaped base 1with a bottom of the base being somewhat lower than a top surface of thebase. The base 1 is preferably made by a thermo forming process as willbe described later. Typically the base 1 is made from a plasticsmaterial which may be gas permeable or it may be a partial gas barriermaterial. Examples of gas permeable materials are a multi-layer webcomprising one layer of P.V.C. and another layer of P.E. The P.V.C. canhave a thickness of about 400 microns while the thickness of the P.E.can be about 70 microns. Throughout this specification the term micronis to be understood as a dimension equal to 1/1000 of a millimeter. Amicron is sometimes referred to as micrometer. Alternatively, thematerial may be a multi-layered web of P.V.C. with a heat sensitivecoating which will enable heat bonding to other plastics components inthe package. The P.V.C. can be of a thickness of 450 microns and thecoating can be of a thickness of about 5 microns. When a partial gasbarrier material is provided, then it may be comprised of multi-layeredweb of P.V.C./P.V.D.C./P.E. The overall thickness of the plasticsmaterial is preferably about 450 microns. If desired, the base may be ofa single web of plastics material such as P.V.C. of about 450 microns.Other suitable materials can be chosen if desired. It should beunderstood that polyethylene will provide for a relatively low gasbarrier, P.V.C. will provide for high gas barrier and P.V.C. in amultilayered form such as P.V.C./P.V.D.C. will provide an even highergas barrier. Aluminium materials such as of about 20 micron thicknesswill provide for an even higher gas barrier material. All of thesematerials are suitable for any of the webs of any of the embodimentsdisclosed herein.

Goods 3 are provided in the base 1. The goods 3 are typically meat,fish, poultry or fresh vegetables although other types of goods such asfoodstuffs can be packaged if desired. Typically the goods 3 have aboutthe same shape and are of the same size as the bottom of the base 1 sothat the base 1 is substantially filled with goods over the bottom ofthe base 1.

A web of flexible plastics material 5 skin packages the goods 3 to thebase 1. The flexible plastics material 5 is typically ofpolyethylene/E.V.A. of 50-100 micron thickness. Alternatively, it maycomprise a plasticized P.V.C. of 50-100 micron thickness which ispreferably heat sealable to the base 1. It may be otherwise sealable tothe base if desired. The above described web 5 is a gas permeable web.If a partial gas barrier web is required then it may comprise amulti-layered web of P.E./P.V.D.C./E.V.A. of about 50-100 micronthickness overall. Other suitable plastics materials for the web can beused if desired.

A lid 7 is fitted over the top of the base 1 so as to provide a freespace 9 between the web 5 and the lid 7. The lid 7 and the web 5 aresealed to the base 1 around a peripheral lip 11 of the base 1.Conveniently the sealing is by way of a heat sealing although otherforms of sealing are envisaged. The free space 9 can contain air ifdesired and/or a suitable gas which will enhance the keeping of thepackaged goods. Typically the volume of the free space 9 is arranged tobe at least equal to the volume of gas necessary to maintain the keepingof the packaged goods for several days or several weeks depending on thenature of the goods and the sale time conditions applicable followingpackaging.

The lid 7 is typically of 80-120 microns in thickness. If it is of a gaspermeable material it may comprise a multi-layer of P.V.C./P.E.Alternatively, it may comprise a multi-layer of P.V.C. with a heatsensitive coating, such as an adhesive, to effect sealing to theflexible web 5 which is, in turn, sealed to the peripheral lip 11 of thebase 1. Alternatively, it may be a single web of plastics material suchas P.V.C.

If the lid material is to be a partial gas barrier, then one suitableform may comprise polyester/P.V.D.C./P.E. or other suitable materials.If a very high gas barrier is required then the lid can be aluminiumwhich may be coated with a plastics material to enhance bonding toperipheral lip 11.

In a further variation of the container referred to in FIG. 1, thematerials may be as follows. The base 1 may be of P.V.C. whilst the web5 may be of a plasticized P.V.C. (P.P.V.C.), and the lid may be P.V.C.The thicknesses of the plastics materials may be generally of the samethickness as previously described.

In a further variation of materials, if the lid 7 and the web 5 are tobe peeled off the base 1 as a single unitary structure, then the base 1may be either P.V.C./E.V.A. which is co-extruded or an extrusionlaminate or a laminate. The flexible web 5 may be plasticized P.V.C.(P.P.V.C.), and the lid 7 may be P.V.C. The thicknesses of the base 1,the web 5 and the lid 7 may be as previously described.

In a further embodiment where the lid only is to be peeled off leavingthe flexible web 5 intact with the base 1, then the base 1 may be ofP.V.C., the flexible web 5 of a plasticized P.V.C. (P.P.V.C.), whilstthe lid 7 is of a P.V.C./E.V.A. laminate which can be formed as aco-extrusion or an extrusion laminate. When the lid 7, or the lid 7 andthe flexible web 5 are peeled off, oxygen can contact the goods 3 withinthe base 1 by either directly contacting the goods or by passing throughthe flexible web 5. It is known that red meat turns dark brown whenoxygen is depleted from the blood. The red colour can be restored byallowing oxygen to contact the blood on the surface of the meat byremoving the lid 7, or the lid 7 and the flexible web 5.

Referring now to FIG. 2 there is shown a construction very similar tothat of FIG. 1 and accordingly like numerals have been given to the samecomponents. In this construction, the goods 3 are received on a furtherweb 13 of plastics material which may be the same material as web 5. Inthis embodiment the goods 3 are completely skin packed around theirexternal surface by the web 5 of plastics material and the further webof plastics material 13. It is noted that a further free space 15 isprovided underneath the goods 3 below the further web 13 of plasticsmaterial. This free space 15 may be filled with gas such as air and/orother gas to enhance the keeping of the packaged goods 3. This gas maybe the same as or different from the gas in the free space 9.

FIG. 3 shows an embodiment similar to that of FIG. 2 but wherein thereare a plurality of layers of packaged goods 3. In this embodiment, eachof the layers of goods 3 is individually skin wrapped by its ownindividual web of plastics material designated generally by numeral 17.Each of the webs of plastics material 17 may comprise the same materialsas that proposed for the webs 5 and 13. In this embodiment the lid 7 mayinclude a pouch 19 into which condiments can be provided. Typically thecondiments can be sauces for the packaged goods. The pouch 19 can have aremovable cover 21 which may conveniently comprise a web of paper or thelike with a suitable adhesive medium on the underside to bond to the lidmaterial around the periphery of the pouch 19.

FIG. 4 shows an embodiment similar to that of FIG. 2 but wherein thereis additionally provided an upper lid 23 which contains eatingimplements such as a knife, fork or spoon 25.

FIG. 5 shows an embodiment similar to that of FIG. 1 but wherein thereis additionally provided an tray 27 suitable for placement in an oven.The tray 27 may conveniently be comprised of metal foil or of a plasticsmaterial such as crystallizable polyethylene terephthalate C.P.E.T. ofabout 400 microns in thickness. This material C.P.E.T. is known for itsdual over usable qualities i.e.--thermal and microwave--and is used inthe food packaging industry.

In the case of embodiments shown in FIGS. 1 through 5 the base 1 may beof a semi rigid construction while the webs 5, 13 and 17, 7 arerelatively flexible. In the case of the embodiment shown in FIGS. 3 and4, the lid 7 or lid 23 may be of a semi rigid construction.

If desired, punched openings may be made through the various webs 5, 13and 17 around the peripheral sides of the goods 3 in such a manner thatthe goods 3 are still sealed within the webs, but so that there areopenings extending therethrough but not into the spaces therebetween.This will allow the gas which is in the free spaces 9 and 15 to freelycirculate around the webs covering the goods 3.

Referring now to FIG. 6 there is shown a side view in diagrammatic formof a preferred packaging machine which performs a preferred packagingmethod in accordance with the present invention. The machine is arrangedso that a web of plastics material 31 can pass underneath a heatingmember 33, be heated and then pass to a thermo forming station 35 wheretrays 1 can be produced by inserting a male die member 37 into a femaledie cavity 39. The so formed bases 1 then move to a goods loadingstation 41. The bases 1 are loaded with the goods such as food and thenpass into a skin packing station 43. At the skin packing station 43, aweb of plastics material 45 is arranged to run parallel with the web 31.FIG. 7 shows a close up view of the skin packing station 43. Here thereis an upper chamber 47 and a lower chamber 49. The lower chamber 49 hasa cavity 51 into which the bases 1 are received. The upper chamber 47contains a heated member 53 which is used to heat the web 45 to adeformable temperature for skin packing. The upper chamber 47 and thelower chamber 49 are then closed and air is evacuated via gaspassageways 55 and 57. The web 45 is maintained separate from the top ofthe base 1 during this evacuation process. The web 45 is then caused tomove towards the heated member 53 to heat it to a deformabletemperature. The undersurface of heated member 53 could be scollapedupwardly--i.e. concavely shaped so as to mirror imitate, at least to asmall degree, the displacement required for the web 5 to skin pack tothe goods 3. When the air has been evacuated, the heated member 53 ismoved downwardly to then heat seal the web 45 around the periphery ofthe base 1 to the lip 11. Air or a gas is then reintroduced throughpassageway 55, at least, and this, in turn, causes the web 45 to skinpack the goods 3 to the base 1. The reason that it skin packs the goods3 is that there is substantially no air between the web 45 and thebase 1. Accordingly, when the air or gas is introduced through thepassageway 55 the flexible web 45 skin packs the goods 3 by beingdisplaced onto the upper surface of the goods 3.

The bases 1 then move to a lid sealing station 59. At this station, aweb of plastics material 61 is provided over the top of the base 1, overthe web 45. FIG. 8 shows a detailed cross-sectional view of the lidsealing station 59. The lid sealing station 59 comprises an upperchamber 63 and a lower chamber 65. It also includes a heated platen 67.The platen 67 is conveniently heated only around the lip 11 region ofthe base 1. In use, the upper chamber 63 and the lower chamber 65 areclosed together and air is evacuated through the air passageway 69. Ifdesired a desired flushing gas can then be admitted into the closedupper chamber 63 and lower chamber 65 so as to provide a desired gasbetween the lid and the base, i.e. between the web 61 and web 31. Theplaten 67 can then be lowered to heat seal the lid to the lip 11 of thebase 1.

It should be appreciated that when the lid 7 is sealed to the base 1,there will be provided a free space, as shown by 9 in FIG. 1, and thefree space contains a desired gas such as O₂, N₂ or CO₂ or other likegases which will enhance the keeping qualities of the packaged goods. Ifdesired it may simply comprise atmospheric air.

The package is then removed from the lid sealing station 59 andseparated from the web 31 by suitable means.

If desired, the skin packing station 43 can also include the step ofadmitting a desired flushing gas through the gas passageways 55 or 57immediately prior to the sealing of the web 45 to the lip 11 of thebase 1. This will provide a desired flushing gas within the spacebetween the base 1 and the web 45.

It can be appreciated that by adding various stations to the apparatusshown in FIG. 6, any one of the embodiments shown in FIGS. 1 through 5can be produced. For example, to produce the embodiment of FIG. 2 afurther web of plastics material 13 need be provided prior to loading ofthe goods 3 into the base 1. The web 13 and 5 can be simultaneouslywelded to the peripheral lip 11 by a single heated platen. In producingthe embodiment of FIG. 3 each of the webs 17 and goods 3 can beindividually layered and then heat sealed to the peripheral lip 11.Additions, any one of the embodiments of FIGS. 1 through 5 can beproduced. Such production is relatively economic and will yield a highthroughput of packages.

When packaging goods such as fish, it is possible to retain the usualdrip liquid with the fish but to allow for controlled atmosphere or gasto permeate through the skin webs. This, in turn, will allow forfreezing of the contents without the growth of ice crystals or the likeas is normal in frozen fish packaging. The appearance of the package isparticularly enhanced by the double glazing effect provided by the lid 7and the web 5 and 13 or webs 17. In the embodiments of FIGS. 2, 3 and 4the goods 3 are effectively within an inner pouch. If desired the goods3 can be frozen in a separately filled and sealed frozen pouch or in ajig of the same size as the semi rigid ovenable tray 27--see FIG. 5.Thus the goods 3 may be maintained in a separate pouch of plasticsmaterial prior to the freezing.

All the plastics materials from which the packaging is made mayindividually or collectively restrict and/or inhibit or control or allowselected atmosphere or gases to flow into or out of the package.

Referring now to FIG. 9 there is shown a preferred form of analternative embodiment of packaging. Here there is provided a P.V.C.base 1 with a skin packing 71. The skin packing 71 may be a partial gasbarrier material of the type previously described. Goods 3 are placedwithin the base 1 above the skin packing 71. A further web of skinpacking 77 is provided over the goods 3. The further web 77 is bonded tothe web 71 and therefore a unitary package is provided by the base 1,the skin packing 71 and the further skin packing 77. Preferably, the webof skin packing 77 is a partial gas barrier material of the typepreviously described. If desired a lid 81 can be provided over the topof the base 1 as shown. Preferably the lid 81 is a gas barrier materialand a gas such as O₂, N₂, CO₂ or like gas which will assist the keepingof the goods is provided in the space 83 which is formed between theskin packing material 77 and the peripheral lip 85 of the base 1 underthe lid 81.

Referring now to FIG. 10 there is shown a diagrammatic side view of apreferred machine for producing the package shown in FIG. 9. Here a webof plastics material 87 is produced with a number of depressions thereinto form bases 1. Typically the web of plastics material 87 is P.V.C.which is relatively inexpensive. A heater 33 is provided for heating theweb 87 whereupon the web 87 passes to a thermo forming station 35 wherethe bases 1 are produced by inserting a male die member 37 into a femaledie cavity 39.

The bases 1 are then passed to a skin packing station 73 where a web ofskin packing plastics material 71 skin packs to the base 1. The skinpacking station 73 is of a type similar to that shown in FIG. 7 andtherefore has not been described in detail here. When the plasticsmaterial 71 is skin packed to the base 1, the base 1 is then passed to astation 74 where goods 3 are provided onto the base 1. The bases 1 andgoods 3 then pass to a further skin packing station 75 where a web ofplastics material 77 is skin packed to the top of the goods 3 and to theperipheral lip 85 around each of the bases 1. The bases 1 then advanceto a lid sealing station 79 where lid material 81 is applied and bondedaround the peripheral lip of the bases 1. If the webs 71, 77 and 81 areof a gas barrier material or selected ones of those webs is a gasbarrier material and suitable gases are employed in the packaging eitherbetween the webs 71 and 77 and/or between webs 77 and 81, then the shelflife of the packaged goods 3 may be able to be enhanced.

FIG. 11 shows an insert 89 which can be placed into the bases 1 prior tothe web 71 being skin packed thereto. In this connection the insert 89is shaped so as to closely follow the contour of the bases 1. Thus whenthe skin packing material 71 is skin packed to the base 1, the insert 89will be held firmly thereto. The insert 89 can have advertising materialprinted thereon so as to obviate the need for subsequent labeling of thepackage. Typically the insert 89 can be of a cardboard material and/or apaper and/or plastics and/or a metal or foil or waxed material. Byappropiate choice of the material of insert 89 it may be possible toavoid the necessity for skin packing a web of skin pack material 71 tothe base 1. Accordingly, by providing the insert 89, the web 71 may bedispensed with.

Suitable gases for use in any of the embodiments herein are acombination of gases, or a single gas, including such atmospheric gasesas Nitrogen, Carbon Dioxide and Oxygen, as well as other suitable gases.

Modifications may be made to the invention as would be apparent topersons skilled in the packaging and/or foodstuff art. These and othermodifications are deemed to be within the scope of the invention, thenature of which is to be determined from the appended claims.

I claim:
 1. An improved package for perishable goods comprising:a baseover which said goods are placed; a gas permeable flexible web coveringand at least partially skin packing said goods and holding said goodsrelative to said base, said web being sealed to said base; a lidpositioned over the top of said base and sealed to said base over saidflexible web; a space above said goods formed between said flexible weband said lid; and a gas retained in said space, said gas selected forenhancing preservation of the packaged goods by permeation of said gasthrough said gas permeable web.
 2. The improved package of claim 1 inwhich the base is made of a gas permeable plastic material.
 3. Theimproved package of claim 1 in which the base is formed of a materialthat creates a partial gas barrier.
 4. The improved package of claim 1in which the base is formed of a high gas barrier material.
 5. Theimproved package of claim 1 in which said base is about 450 micronsthick.
 6. The improved package of claim 1 in which said web forms apartial gas barrier.
 7. The improved package of claim 1 in which saidweb is from 50-100 microns thick.
 8. The improved package of claim 1 inwhich said lid is gas permeable.
 9. The improved package of claim 1 inwhich said lid forms a very high gas barrier.
 10. The improved packageof claim 1 in which said lid forms a partial gas barrier.
 11. Theimproved package of claim 1 in which said lid is from 80-120 micronsthick.
 12. The improved package of claim 1 in which the space betweensaid lid and said web contains an amount of gas needed to preserve thegoods for an extended period, the nature of the goods determining thegas selected.
 13. The improved package of claim 12 in which said gas isoxygen, nitrogen, carbon dioxide, atmospheric air or another gas, orcombinations thereof, selected for its preservation characteristics. 14.The improved package of claim 1 in which said lid is affixed to saidbase so that it may be removed from the package separately from saidweb.
 15. The improved package of claim 1 in which said lid and said webare peelable as a unit from said base.
 16. The improved package of claim1 in which said base is made of P.V.C., said flexible web is made ofplasticized P.V.C. and said lid is made of P.V.C.
 17. The improvedpackage of claim 1 in which said base is made of a P.V.C./E.V.A.laminate, said web is made of plasticized P.V.C. and said lid is made ofP.V.C.
 18. The improved package as in claim 1, in which said base ismade of P.V.C., said web is made of plasticized P.V.C. and said lid ismade of a P.V.C./E.V.A. laminate.
 19. The improved package of claim 1including a further gas permeable flexible web sealed relative to saidbase, said further web underlying and, in cooperation with said firstweb, substantially completely skin packing said goods.
 20. The improvedpackage of claim 19 in which said further web is dimensioned so as toform a space between it and the base, said space being filled with a gasselected for enhancing preservation of the packed goods.
 21. Theimproved package of claim 19 in which the gas between said further weband said base is different from that between said first web and saidlid.
 22. The improved package of claims 1 or 19 in which said lidprovides a containing space for an eating implement.
 23. The improvedpackage of claims 1 or 19 further including an oven-microwave usabletray positioned between said base and said skin packed goods.
 24. Theimproved package of claim 19 in which said base contains a plurality ofskin packed goods, said goods being arranged on said base one on top ofthe other, said goods each being individually skin packed.
 25. Theimproved package of claim 19 in which said bottommost skin packed goodsare so positioned as to provide a gas retaining space between said baseand said goods, said space being filled with a gas selected to enhancethe preservation of the goods.
 26. The improved package of claim 25 inwhich said gas may be oxygen, nitrogen, carbon dioxide, atmospheric airor another suitable gas.
 27. The improved package of claim 1 in whichsaid web is urged into skin packing conformation with said goods byreducing the gas pressure below said web.